1. Field of the Invention
The present invention relates to a modular deployable antenna, to particularly the one applicable as a transmit-receive antenna 10 to 15 m long mounted in a mobile communications satellite, as an antenna for a remote-sensing satellite for investigating resources, and to a geostationary platform and a solar beam converging panel for a space station.
2. Description of the Related Art
The development of a large-sized deployable antenna applicable to a variety of purposes such as communication, broadcasting, and further survey of the earth and deep space is accelerated for the purpose of communicating more information at present. The basic idea in design of the large-sized deployable antenna varies considerably depending upon practicability, profitability or a purpose of use. For example, for an antenna applied to a communication or broadcasting satellite requiring a large-sized deployed reflector, efficiency of stowing an antenna into a launched satellite, light weight, reliability of a deploying mechanism and precision after deployment are primarily required. For such an antenna applied to such a satellite requiring a high-precision reflector, choice of material suitable for the location of use and reflector forming technique are required. In case an antenna is assembled in an orbit, the technique of assembling in an orbit is primarily required.
Referring to a large-sized deployed reflector, various types are developed at present. A deployable truss mesh type in which metallic mesh is spread on a deployable trussed back structure, an inflatable type which is hardened in a predetermined shape by expanding it with gas pressure, and a tension truss type constituted by an extensible mast mounted on the central support structure and extending outside the radius and specular mesh spread over the central support structure by the mast are contained.
Referring to the deployable truss mesh type above all, generally the back structure is constituted by combining plural modules constituted by a triangle or hexagonal prism serially, and mesh is fixed on a stand-off which is different in height respectively provided with an individual module.
Referring to the deployable truss mesh type, it is first required that sufficient precision of a reflector is kept even if the reflector is enlarged. It is also required that a reflector is rigid through it is kept light or lightened more. Further, the deploying and stowing operation must be smooth and reliable. Furthermore, to realize effective modularization, linkage or detachment of modules must be facilitated.
At present an antenna approximately 5 to 30 m in diameter is developed all over the world, however, in any case, the frequency band is L band.